<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      border: 3px solid #000000;
      border-radius: 10px;
      padding: 20px;
      margin: 20px;
      width: 200px;
    }

    h3 {
      margin: 10px 0 20px 0;
    }

    p {
      margin: 20px;
    }
  </style>
</head>

<body>

  <div id="app">
    <div class="box">
      <h3>小黑自动售货机</h3>
      <button @click="buy('可乐', 5)">可乐5元</button>
      <button @click="buy('咖啡', 10)">咖啡10元</button>
      <button @click="buy('牛奶', 8)">牛奶8元</button>
    </div>
    <p>银行卡余额: {{ money }}元</p>
  </div>

  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        money: 100
      },
      methods: {
        buy(goods, price) {
          console.log(`购买${goods}成功!`)
          this.money -= price
        }
      }
    })
  </script>
</body>

</html>